Br[Zn][CH2:3][C:4]([O:6][CH2:7][CH3:8])=[O:5].[C:9]1(=[O:16])[CH:14]=[CH:13][C:12](=[O:15])[CH:11]=[CH:10]1.Cl.C(OCC)(=O)C>C1COCC1>[CH2:7]([O:6][C:4](=[O:5])[CH2:3][C:9]1([OH:16])[CH:14]=[CH:13][C:12](=[O:15])[CH:11]=[CH:10]1)[CH3:8]
Under nitrogen atmosphere, 6 mL of THF was added to 1.22 g (2 mmol, 0.6 equivalent) of (BrZnCH2COOEt.THF)2. Under argon atmosphere, a solution of 0.36 g (3.33 mmol) of p-benzoquinone in 2.5 mL of THF was added dropwise while stirring at 0˜5° C. The mixture was stirred at 20˜25° C. for 1 hour. 5 mL of 1N hydrochloric acid was added dropwise at 20° C. or lower, followed by dilution with 25 mL of ethyl acetate. Then, the layers were separated. The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution. After washing, the organic layer was dried with anhydrous magnesium sulfate. After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2) afforded 0.46 g of the desired product (yield 70%).
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